On Thu, 22 Aug 2024 17:02:52 +0200
Miroslav Šulc <miroslav.sulc@xxxxxxxxxxxx> wrote:
> hello,
>
> a broken synology raid5 ended up on my desk. the raid was broken for
> quite some time, but i got it from the client just a few days back.
>
> the raid consisted of 5 disks (no spares, all used):
> disk 1 (sdca): according to my understanding, it was removed from the
> raid, then re-added, but the synchronization was interrupted, so it
> cannot be used to restore the raid
Hi Miroslav,
(If I send something earlier - sorry missclick)
Array State : AAAAA ('A' == active, '.' == missing, 'R' == replacing)
Events : 60223
There is no info about interrupted rebuild in the metadata. This drive
looks like removed from array, it has old Events number. If it was
rebuilt, it finished correctly.
The metadata on the drive is frozen on the last state of the device in array,
other members were updated that this device is gone.
> disk 2 (sdcb): is ok and up to date
> disk 3 (sdcc): seems to be up to date, still spinning, but there are
> many issues with bad sectors
Events : 60283
Layout : left-symmetric
Chunk Size : 64K
Device Role : Active device 2
Array State : .AAAA ('A' == active, '.' == missing, 'R' == replacing)
It is outdated, Events number is smaller than on "ok" members. Sadly, probably
mdadm will refuse to start this array because you have 2 outdated drives.
On "ok" disks, it is:
Events : 60286
Array State : .AAAA ('A' == active, '.' == missing, 'R' == replacing)
Second failure is not recorded in metadata and I don't know why events number is
higher. I would expect kernel to stop updating metadata after device failure.
I will stop here and give a chance more native experienced users to elaborate.
Looks like raid recreation with --assume-clean is a simplest solution but it
is general advice I can give you (and I propose it too often). You have copies,
you did right first step!
Mariusz
> disk 4 (sdcd): is ok and up to date
> disk 5 (sdce): is ok and up to date
>
> the raid ran in degraded mode for over two months, client trying to make
> a copy of the data from it.
>
> i made copies of the disk images from disks 1, 2, 4, and 5, at the state
> shown below. i didn't attempt to make a copy of disk 3 so far. since
> then i re-assembled the raid from disk 2-5 so the number of events on
> the disk 3 is now a bit higher then on the copies of the disk images.
>
> according to my understanding, as the disk 1 never finished the sync, i
> cannot use it to recover the data, so the only way to recover the data
> is to assemble the raid in degraded mode using disk 2-5, if i ever
> succeed to make a copy of the disk 3. i'd just like to verify that my
> understanding is correct and there is no other way to attempt to recover
> the data. of course any hints are welcome.
>
> here is the info from the partitions of the raid:
>
> /dev/sdca5:
> Magic : a92b4efc
> Version : 1.2
> Feature Map : 0x2
> Array UUID : f697911c:bc85b162:13eaba4e:d1152a4f
> Name : DS_KLIENT:4
> Creation Time : Tue Mar 31 11:40:19 2020
> Raid Level : raid5
> Raid Devices : 5
>
> Avail Dev Size : 15618390912 (7447.43 GiB 7996.62 GB)
> Array Size : 31236781824 (29789.72 GiB 31986.46 GB)
> Data Offset : 2048 sectors
> Super Offset : 8 sectors
> Recovery Offset : 4910216 sectors
> Unused Space : before=1968 sectors, after=0 sectors
> State : clean
> Device UUID : 681c6c33:49df0163:bb4271d4:26c0c76d
>
> Update Time : Tue Jun 4 18:35:54 2024
> Checksum : cf45a6c1 - correct
> Events : 60223
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Device Role : Active device 0
> Array State : AAAAA ('A' == active, '.' == missing, 'R' == replacing)
> /dev/sdcb5:
> Magic : a92b4efc
> Version : 1.2
> Feature Map : 0x0
> Array UUID : f697911c:bc85b162:13eaba4e:d1152a4f
> Name : DS_KLIENT:4
> Creation Time : Tue Mar 31 11:40:19 2020
> Raid Level : raid5
> Raid Devices : 5
>
> Avail Dev Size : 15618390912 (7447.43 GiB 7996.62 GB)
> Array Size : 31236781824 (29789.72 GiB 31986.46 GB)
> Data Offset : 2048 sectors
> Super Offset : 8 sectors
> Unused Space : before=1968 sectors, after=0 sectors
> State : clean
> Device UUID : 0f23d7cd:b93301a9:5289553e:286ab6f0
>
> Update Time : Wed Aug 14 15:09:24 2024
> Checksum : 9c93703e - correct
> Events : 60286
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Device Role : Active device 1
> Array State : .AAAA ('A' == active, '.' == missing, 'R' == replacing)
> /dev/sdcc5:
> Magic : a92b4efc
> Version : 1.2
> Feature Map : 0x0
> Array UUID : f697911c:bc85b162:13eaba4e:d1152a4f
> Name : DS_KLIENT:4
> Creation Time : Tue Mar 31 11:40:19 2020
> Raid Level : raid5
> Raid Devices : 5
>
> Avail Dev Size : 15618390912 (7447.43 GiB 7996.62 GB)
> Array Size : 31236781824 (29789.72 GiB 31986.46 GB)
> Data Offset : 2048 sectors
> Super Offset : 8 sectors
> Unused Space : before=1968 sectors, after=0 sectors
> State : clean
> Device UUID : 1d1c04b4:24dabd8d:235afb7d:1494b8eb
>
> Update Time : Wed Aug 14 12:42:26 2024
> Checksum : a224ec08 - correct
> Events : 60283
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Device Role : Active device 2
> Array State : .AAAA ('A' == active, '.' == missing, 'R' == replacing)
> /dev/sdcd5:
> Magic : a92b4efc
> Version : 1.2
> Feature Map : 0x0
> Array UUID : f697911c:bc85b162:13eaba4e:d1152a4f
> Name : DS_KLIENT:4
> Creation Time : Tue Mar 31 11:40:19 2020
> Raid Level : raid5
> Raid Devices : 5
>
> Avail Dev Size : 15618390912 (7447.43 GiB 7996.62 GB)
> Array Size : 31236781824 (29789.72 GiB 31986.46 GB)
> Data Offset : 2048 sectors
> Super Offset : 8 sectors
> Unused Space : before=1968 sectors, after=0 sectors
> State : clean
> Device UUID : 76698d3f:e9c5a397:05ef7553:9fd0af16
>
> Update Time : Wed Aug 14 15:09:24 2024
> Checksum : 38061500 - correct
> Events : 60286
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Device Role : Active device 4
> Array State : .AAAA ('A' == active, '.' == missing, 'R' == replacing)
> /dev/sdce5:
> Magic : a92b4efc
> Version : 1.2
> Feature Map : 0x0
> Array UUID : f697911c:bc85b162:13eaba4e:d1152a4f
> Name : DS_KLIENT:4
> Creation Time : Tue Mar 31 11:40:19 2020
> Raid Level : raid5
> Raid Devices : 5
>
> Avail Dev Size : 15618390912 (7447.43 GiB 7996.62 GB)
> Array Size : 31236781824 (29789.72 GiB 31986.46 GB)
> Data Offset : 2048 sectors
> Super Offset : 8 sectors
> Unused Space : before=1968 sectors, after=0 sectors
> State : clean
> Device UUID : 9c7077f8:3120195a:1af11955:6bcebd99
>
> Update Time : Wed Aug 14 15:09:24 2024
> Checksum : 38177651 - correct
> Events : 60286
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Device Role : Active device 3
> Array State : .AAAA ('A' == active, '.' == missing, 'R' == replacing)
>
>
> thank you for your help.
>
> miroslav
>
